import math
x1,y1,x2,y2=map(float,input().split())
A=abs(y1-y2)
B=abs(x1-x2)
C=math.sqrt(A**2+B**2)
print(f'{C:.8f}') import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 A=abs(y1-y2) A abs(y1-y2) abs y1-y2 y1 y2 B=abs(x1-x2) B abs(x1-x2) abs x1-x2 x1 x2 C=math.sqrt(A**2+B**2) C math.sqrt(A**2+B**2) math.sqrt math sqrt A**2+B**2 A**2 A 2 B**2 B 2 print(f'{C:.8f}') print f'{C:.8f}' x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1 B=abs(x1-x2) abs(x1-x2) B C=math.sqrt(A**2+B**2) math.sqrt(A**2+B**2) C A=abs(y1-y2) abs(y1-y2) A x2,y2=map(float,input().split()) map(float,input().split()) x2 y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 y2=map(float,input().split()) map(float,input().split()) y2
import math
x1,y1,x2,y2=map(float,input().split())
A=abs(y1-y2)
B=abs(x1-x2)
C=math.sqrt(A**2+B**2)
print(f'{C:.8f}')
